1. Field of the Invention
The present invention relates to an elevator control apparatus that utilizes a power storage unit and, more particularly, to an elevator control apparatus adapted to control the temperature of the power storage unit.
2. Description of the Related Art
A conventional elevator control apparatus will be described with reference to an accompanying drawing. FIG. 20 shows a construction of a conventional elevator control apparatus disclosed in, for example, Japanese Unexamined Patent Application Publication No. 61-267675.
The controlling apparatus shown in FIG. 20 includes a commercial three-phase AC power source 1, a converter 2 composed of diodes or the like, a capacitor 3, an inverter 4, a motor 5, such as an induction motor, a hoisting machine 6, an elevator car 7, a counterweight 8, and a rope 9. The controlling apparatus further includes a power storage unit 10 composed of a battery, a charging and discharging (hereinafter referred to as xe2x80x9ccharge/discharge) circuit 11 composed of a DC/DC converter or the like for performing power conversion in both directions between two different DC voltages of a battery voltage and an inverter input voltage, a charge/discharge control circuit 12 for controlling the charge/discharge circuit 11 as to the direction of power conversion and battery currents, a voltage detector 13, a voltage detector 14 for the power source, a battery current detector 15, and a battery charge amount detector 16.
An operation of the foregoing conventional elevator control apparatus will now be described with reference to the accompanying drawing.
If the AC power source 1 incurs a power failure, power is supplied to an input section of the inverter 4 from the power storage unit 10 through the charge/discharge circuit 11. Thus, the motor 5 is driven by the inverter 4 to land an elevator.
In normal operation, if an inverter input voltage drops while the elevator is accelerating, power is supplied to the input section of the inverter 4 from the power storage unit 10 through the charge/discharge circuit 11 to restrain a voltage-drop at the input section of the inverter 4.
Conversely, if the inverter input voltage rises due to regenerative electric power from the motor 5 while the elevator is being braked, power is supplied from the input section of the inverter 4 to the power storage unit 10 through the charge/discharge circuit 11 so as to charge the power storage unit 10. When the charge amount of the power storage unit 10 becomes low, power is also supplied to the power storage unit 10 from the input section of the inverter 4 through the charge/discharge circuit 11 so as to charge the power storage unit 10.
The conventional elevator control apparatus described above employs a battery for the power storage unit. Charge and discharge characteristics of the battery vary depending on temperature. There has been a problem in that charging all regenerative electric power of the elevator causes a sudden rise in the temperature of the battery especially at a low temperature, and a gas is generated in the battery, leading to significant deterioration of the battery.
Accordingly, the present invention has been made with a view toward solving the problem mentioned above, and it is an object of the present invention to provide an elevator control apparatus that is capable of measuring an atmospheric temperature and a temperature of a battery to control charging and discharging so as to restrain deterioration of the battery, and also capable of conducting control of economical charging and discharging of the, battery thereby to minimize waste of power.
To this end, according to one aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power to convert it into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor base on the AC power of a variable voltage and a variable frequency so as to operate an elevator; a power storage unit for storing the DC power; temperature detecting means for detecting a temperature of the power storage unit; a charge/discharge control circuit for controlling a charge/discharge electric energy based on the detected temperature and issuing a drive signal; and a charge/discharge circuit for charging and discharging the power storage unit based on the drive signal.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power to convert it into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of a variable voltage and a variable frequency so as to operate an elevator; a power storage unit for storing the DC power; temperature detecting means for detecting an environmental temperature; a charge/discharge control circuit for controlling a charge/discharge electric energy based on the detected temperature and issuing a drive signal; and a charge/discharge circuit for charging and discharging the power storage unit based on the drive signal.
In a preferred form of the present invention, the charge/discharge control circuit issues a drive signal so that charging is carried out within a permissible range of a charge state of the power storage unit if a detected temperature of the power storage unit is lower than a preset predetermined temperature.
In another preferred form of the present invention, the charge/discharge control circuit changes a setting range of the charge state of the power storage unit based on the detected temperature.
In yet another preferred form of the present invention, the charge/discharge control circuit changes an upper limit value of the charge state of the power storage unit based on a mean temperature of the temperatures detected during a preset predetermined period of time.
In still another preferred form of the present invention, the charge/discharge control circuit changes the upper limit value of the charge state of the power storage unit based on a lowest temperature of the temperatures detected during a preset predetermined period of time.
In a further preferred form of the present invention, the charge/discharge control circuit carries out control so that an input voltage of the inverter is set at a constant voltage of a preset predetermined voltage, carries out control so that, when charge current to the power storage unit reaches a preset predetermined upper limit value based on the detected temperature, the charge current does not exceed the upper limit value, and issues a drive signal for charging the power storage unit with regenerative electric power.
In another preferred form of the present invention, the charge/discharge control circuit carries out control to charge the power storage unit with regenerative electric power so that an input voltage of the inverter is set at a constant voltage of a preset predetermined voltage, and issues a drive signal for stopping charging the power storage unit with regenerative electric power when a voltage of the power storage unit reaches a preset predetermined upper limit value based on the detected temperature.
In yet another preferred form of the present invention, the charge/discharge control circuit carries out control so that charge current supplied to the power storage unit is set at a constant current of a preset predetermined current value, and issues a drive signal for charging the power storage unit with the regenerative electric power while conducting control to set the charge current supplied to the power storage unit at a constant current restricted to be lower than the predetermined current value if the detected temperature is not more than a first preset predetermined temperature or not less than a second preset predetermined temperature that is higher than the first predetermined temperature.
In still another preferred form, the elevator control apparatus further includes a resistor disposed in the vicinity of the power storage unit, wherein the charge/discharge control circuit causes the resistor to consume regenerative electric power if the detected temperature of the power storage unit is a predetermined temperature or less.
In yet another preferred form, the elevator control apparatus further includes a second resistor disposed at a location away from the power storage unit, wherein the charge/discharge control circuit causes the resistor disposed in the vicinity of the power storage unit to consume regenerative electric power if the detected temperature of the power storage unit is below a predetermined temperature, or causes the second resistor to consume the regenerative electric power if the detected temperature of the power storage unit is a predetermined temperature or more and the power storage unit cannot be charged with the regenerative electric power.
According to another aspect of the present invention, there is provided an elevator control apparatus including: a converter for rectifying AC power to convert it into DC power; an inverter for converting the DC power into AC power of a variable voltage and a variable frequency; a controller for controlling a motor based on the AC power of a variable voltage and a variable frequency so as to operate an elevator; a power storage unit for storing the DC power; clock means for counting day and time; a charge/discharge control circuit for controlling a charge/discharge electric energy based on an acquired day and time from the clock means and for issuing a drive signal; and a charge/discharge circuit for charging or discharging the power storage unit based on the drive signal.
In a preferred form of the above elevator control apparatus, the charge/discharge control circuit changes a setting range of the charge state of the power storage unit based on the detected temperature.
In yet another preferred form of the above elevator control apparatus, the charge/discharge control circuit changes an upper limit value of the charge state of the power storage unit based on a mean temperature of the temperatures detected during a preset predetermined period of time.
In still another preferred form of the above elevator control apparatus, the charge/discharge control circuit changes the upper limit value of the charge state of the power storage unit based on a lowest temperature of the temperatures detected during a preset predetermined period of time.
In a further preferred form of the above elevator control apparatus, the charge/discharge control circuit carries out control so that an input voltage of the inverter is set at a constant voltage of a preset predetermined voltage, and issues a drive signal for carrying out control so that, when charge current to the power storage unit reaches a preset predetermined upper limit value based on the detected temperature, the charge current does not exceed the upper limit value to charge the power storage unit with regenerative electric power.
In another preferred form of the above elevator control apparatus, the charge/discharge control circuit carries out control to charge the power storage unit with regenerative electric power so that an input voltage of the inverter is set at a constant voltage of a preset predetermined voltage, and issues a drive signal for stopping charging the power storage unit with regenerative electric power when a voltage of the power storage unit reaches a preset predetermined upper limit value based on the detected temperature.
In yet another preferred form of the above elevator control apparatus, the charge/discharge control circuit carries out control so that charge current supplied to the power storage unit is set at a constant current of a preset predetermined current value, and issues a drive signal for conducting control to set the charge current supplied to the power storage unit at a constant current restricted to be lower than the predetermined current value to charge the power storage unit with the regenerative electric power if the detected temperature is a first preset predetermined temperature or lower, or a second preset predetermined temperature or more that is higher than the first predetermined temperature.